package com.example.shopdemo.utils;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

/**
 * @author ：Anitaxiaofeng
 * @description：微信请求校验工具类
 * @create 2018-01-30
 **/
public class SignUtil {

    /**
     * 与接口配置信息中的Token要一致
     */
    private static String TOKEN = "shopdemo";

    /**
     * 验证签名
     * @param signature
     * @param timestamp
     * @param nonce
     * @return
     */
    public static boolean checkSignature(String signature,String timestamp,String nonce){
        String[] arr = new String[]{TOKEN,timestamp,nonce};
        //将token、timestamp、nonce三个参数进行字典排序
        Arrays.sort(arr);
        StringBuilder content = new StringBuilder();
        for(int i = 0;i<arr.length;i++){
            content.append(arr[i]);
        }
        MessageDigest md = null;
        String tmpStr = null;
        try{
            md = MessageDigest.getInstance("SHA-1");
            //将三个参数字符串拼接成一个字符串进行sha1加密
            byte[] digest = md.digest(content.toString().getBytes());
            tmpStr = byteToStr(digest);
        }catch(NoSuchAlgorithmException e){
            e.printStackTrace();
        }

        content = null;
        //将加密后的字符串与signature对比，表示该请求来源于微信
        return tmpStr!=null?tmpStr.equals(signature.toUpperCase()):false;

    }

    /**
     * 将字节数组转换为十六进制字符串
     * @param byteArray
     * @return
     */
    public  static String byteToStr(byte[] byteArray){
        String strDigest = "";
        for(int i=0;i<byteArray.length;i++){
            strDigest +=byteToHexStr(byteArray[i]);
        }
        return strDigest;
    }

    /**
     * 将字节转换为十六进制字符串
     * @param mByte
     * @return
     */
    public static String byteToHexStr(byte mByte){
        char[] Digit = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
        char[] tempArr = new char[2];
        tempArr[0] = Digit[(mByte>>>4)&0X0F];
        tempArr[1] = Digit[mByte&0X0F];
        String s = new String(tempArr);
        return s;
    }
}
